An eye tracking technology is a technology involving applications of science. A first application is to perform tracking according to feature changes of an eye and eye surroundings. A second application is to perform tracking according to changes of an iris angle. A third application is to extract features by proactively projecting a beam, such as an infrared ray, onto an iris. Application of the eye tracking technology to mobile devices is used as example. Currently, the eye tracking technology used in a mobile device is mainly applied to operations such as collecting a user's interests, unlocking a screen lock, and determining whether a user is looking at the mobile device or scrolling a display.
However, when the user is inconvenient to operate the mobile device manually (for example, the user is in a meeting, or both hands of the user are being occupied), the user may be unable to start an eye tracking function. Consequently, the user cannot use the mobile device to complete a related service. This is poorly convenient.